Apparatus and method for releasing a lens molded in a cavity between posterior and anterior mold sections

ABSTRACT

An apparatus and method for releasing a lens moulded in a cavity between posterior ( 21 ) and anterior mould ( 22 ) sections and adhered thereto. A post ( 30 ) is configured to support a flange ( 20 ) of the posterior section whilst the anterior section remains spaced from the post. Posterior section is compressed between a pin ( 40 ) applied to, an outer concave surface ( 29   a ) of the posterior section and the post, thereby initially releasing peripheral regions of the posterior section and subsequently the remaining portions thereof. Upon separation, the anterior section together with the lens ( 10 ) drops onto the post so that its outer convex surface ( 29   a ) rests on the post. A collar unit ( 50 ) with gas channels ( 53 ) presses against a flange ( 200 ) of the anterior section whilst blowing jets of gas towards an interface between a “monomer” ring ( 11 ) formed around the lens. In this manner, initially the “monomer” ring and then peripheral regions of the lens are separated from the anterior section.

This present invention relates to an apparatus and a method forreleasing a moulded lens from a cast mould.

Static cast moulding of contact lenses is known. For example, U.S. Pat.No. 5,466,147 issued to Bausch & Lomb Incorporated describes a singlemould unit for making a single lens comprising an anterior mould sectionhaving a concave optical surface and posterior mould section having aconvex optical surface. The anterior and posterior mould sections arecomplementarily shaped and are brought together to form a lens-mouldingcavity between the facing anterior and posterior optical surfaces of theanterior and posterior mould sections, respectively.

The basic process for cast moulding a lens is as follows. A quantity ofliquid lens material 16 is dispensed onto the concave optical surface12A of the anterior mould section 12 (FIG. 1), and the posterior mouldsection 14 is seated upon the anterior mould section 12 with the concaveand convex surfaces 14A and 12A thereof, respectively, facing oneanother to form a lens-shaped mould cavity. The joined anterior andposterior mould sections form a single mould which is subjected to acuring cycle (e.g., by thermal or UV radiation) thereby causingpolymerization of the lens material in the mould cavity (FIG. 2).Subsequently, a number of steps must be carried out in order to retrievethe cured lens from the mould cavity.

Separation of Mould Parts

Once the lens material has cured, the posterior and anterior mouldsections must be separated to retrieve the cured lens. This procedure issometimes referred to as “decapping” in the art. The opening or releaseof the mould sections must be carried out in a manner which will notharm the delicate lens. Once the lens has polymerized in the mouldcavity, the lens and any excess lens material will adhere to theopposing concave and convex mould surfaces. Thus, the force required torelease the posterior mould section from the anterior mould section mustbe strong enough to break the adhesive bond of the lens and excess lensmaterial to the opposing mould surfaces, yet not so forceful orhaphazard that the optical surfaces of the lens are harmed by therelease process. Should the lens crack or otherwise be damaged duringthe mould release process, the lens must be rejected thereby loweringthe output yield and increasing manufacturing costs. Typically, afterthe decapping step, the cured lens is retained in the anterior mouldsection whilst the posterior section is removed. For example, U.S. Pat.No. 5,850,107 (Kindt-Larsen et al.) describes an apparatus forseparating the anterior and the posterior mould parts, wherein each ofthe mould parts has an annular circumferential flange respectivelysurrounding the mould cavity. The apparatus includes a first device forapplying steam to the concave non-optical surface of the posterior mouldpart to provide a temperature gradient from the posterior mould part tothe anterior mould part and a second device comprising pry fingers forinserting between the circumferential flanges and pulling the mouldparts apart. The provision of the temperature gradient is undesirablefor the cured lens since the lens can deform and not re-gain itsrequired curvature upon cooling. If the separation is attempted withoutproviding the temperature gradient, there is a risk that the lens willbe damaged. Furthermore, there is no guarantee that the cured lens willremain adhered to the desired mould part upon the separation step.Another arrangement separating the mould parts apart is disclosed inU.S. Pat. No. 5,693,268 (Widman et al.) in which the mould parts arepulled apart by inserting wedges therebetween.

A further arrangement is described in U.S. Pat. No. 6,428,723(Lesczynski et al.) in which the posterior mould section has adownwardly facing skirt which rests on an annular end surface of amovably mounted hollow cylinder which surrounds the anterior mouldsection. The inner diameter of the cylinder substantially corresponds tothe outer diameter of a downwardly facing skirt of the anterior mouldsection. A pin exerts a force on the posterior section from above as thehollow cylinder moves in the direction of the pin in order to pull themould parts apart. Because of the mutual disposition of the mould parts,the pulling force acts on the entire area of the lens and there stillremains the risk of damaging the lens. In another embodiment disclosedin this reference, instead of the annular end surface, the hollowcylinder has a pointed edge formed by tapered inner and outer surfacesof the cylinder. The edge is inserted between the inner and outersurfaces of the skirts of the posterior and anterior mould sectionsrespectively, thereby radially deflecting the skirt of the posteriormould section and causing the posterior mould section to disengage fromthe lens. In this arrangement, the deflection amplitude of the skirt ofthe posterior mould section is limited, which in turn limits the controlover the posterior mould during the decapping operation.

U.S. Application Publication No. 2003/0160343 describes a separationmodule in which the mould parts are oriented so that the anterior mouldsection 12 (FIG. 3) is upper-most in relation to the posterior, convexmould part 14. An annular flange 14 c of the posterior mould part 14rests on a support plate 260 and a means is provided for striking theanterior mould part 12 from above at an annular flange 12 c so as tobreak the adhesion bond between the mould parts 12,14. In accordancewith another known method, the posterior mould part 14 is locatedupper-most in relation to the anterior mould part 12 and the anteriormould part is supported from below on posts. A means is provided forstriking from above the annular surface surrounding the lens formingsurface of the posterior mould part 14 so as to break the bond betweenthe mould parts. There still remains a risk associated with the lattertwo methods in that the lens may be damaged due to the dynamic forceapplied to the relevant mould part.

Removal of Excess Moulding Material (“Monomer Ring” Removal)

To ensure that the mould cavity is completely filled with the liquidlens material during the moulding process described above, the quantityof liquid lens material dispensed in the anterior mould section ispurposely greater than that needed to form the lens (FIG. 4). When theposterior mould section 14 is seated upon the anterior mould section 12,the excess liquid lens material 180 is expelled from the mould cavity(FIG. 5). This excess liquid is typically held in a “reservoir”, agroove or a flange surrounding the mould cavity, and is cured along withthe lens. The cured excess material 180 is typically referred to as a“monomer ring” or a “HEMA ring” in the contact lens art, depending onthe specific lens material used. The term “monomer ring” will be usedherein for convenience, although it is understood this term is usedbroadly herein to cover any type of lens material employed. During mouldseparation, the monomer ring will usually adhere to one of the mouldsections, typically the anterior section 12, with the monomer ringusually retained in the anterior mould section 12 along with the lens(FIGS. 6 and 7). Should the lens be released and removed from theanterior mould surface without prior removal of the monomer ring fromthe reservoir, the lens edge will likely become damaged due tointerference with the monomer ring (FIG. 8). The presence of the monomerring can also interfere with downstream processes and machinery. It isthus desirable to release and remove the monomer ring from the anteriormould section prior to the release and removal of the lens therefrom.Various monomer ring removal processes have been employed in the priorart, none of which has proven entirely satisfactory. For example, U.S.Pat. No. 6,368,096 and U.S. Pat. No. 6,638,362 (Dobner et al.) describe,respectively, an apparatus and a method for removing the monomer ringfrom a reservoir surface of the anterior mould. The disclosure describespiercing the monomer ring with annularly spaced pins or blades 52 androtating them around the reservoir surface whereby the monomer ring issheared from the anterior mould section 12 to which it was adhered whilethe moulded lens remains intact in the mould cavity (FIG. 9). While thisapparatus is quite useful, difficulties may be encountered when the ringhas a relatively low volume, or when the ring material is very brittle.For example, the pins or blades that pierce the monomer ring may breakthe ring into several smaller pieces. These smaller pieces are moredifficult to remove, and some pieces may remain on the contact lens.

Another method is disclosed in United States patents U.S. Pat. No.5,975,875 (Crowe, Jr. et al.), in accordance with which variously shapednotches or steps are formed on the surface of the posterior mould partwhich surrounds the mould cavity. The notches project into the monomerring when the monomer ring is in a liquid state. When the monomer ringhas cured it adheres to the notches or the steps such that when theposterior mould part is separated from the anterior mould part, themonomer ring is removed with the posterior part. With this arrangement,there still remains a risk that parts of the ring will remain adhered tothe anterior mould part after the separation of the posterior mould partfrom the anterior mould part.

U.S. Patent Application Publication 2006/0071356-A1 (Beebe) describes atooling for removing excess monomer material from the anterior mouldpart. The tooling comprises a plate in a surface of which there isformed a wedge-shaped groove which has a first pair of opposed taperedsurfaces that guide the anterior mould part as it is moved through thegroove. The wedge-shaped groove also has a second pair of opposedtapered surfaces that contact and deflect the monomer ring material asthe anterior mould part is guided by the first pair of tapered surfaces,thereby displacing and removing the excess material from the anteriormould part while the cured lens remains adhered to the anterior mouldpart. As with the '875 device, there still remains a problem that piecesof the monomer ring may remain adhered to the anterior mould part andthat some pieces may become loose and interfere with the cured lens orwith the tooling.

Release of Cured Lens from a Surface of a Mould Section

Once the mould sections have been separated, the lens will adhere to asurface of one of the mould sections and must therefore be released fromthe mould section on which it is retained. As mentioned above, the lenstypically remains adhered to the anterior mould section. Both wet anddry release methods of lens release have been proposed in the prior art.In wet lens release methods, an aqueous solution is used to wet thehydrophilic lens which absorbs water and swells, causing the lens toseparate from the mould surface. In dry release methods, the lens isremoved from the associated mould surface while still in the dry state.In general, dry releasing a lens from the associated mould part ispreferred over wet release methods. This is because the lens is mucheasier to handle when in the dry state as opposed to the wet state. Inthe dry state, it is easy to pick the lens with a vacuum picking headand move the lens from one process station to another. The adhesive bondbetween the lens and mould surface is broken, usually by deformation ofthe mould so as to move the mould surface relative to the lens. Forexample, WO 2004/030898 (Bausch & Lomb Inc.) discloses a method and anapparatus for dry releasing of the anterior, convex surface of a lensfrom an anterior mould part 12 (FIG. 10) which involves applying a firstforce to peripheral regions of the convex non-optical surface 12D of theanterior mould part, and subsequently applying a second force against anapex region 12E of the non-optical convex surface. WO 2005/061212(Bausch & Lomb Inc.) teaches a method and an apparatus for dry-releasinga cured lens from the anterior mould part 12 (see FIG. 11) comprising aservo-driven lens release head 19 positionable in register with theanterior mould part 12 and having a downwardly facing annulus 19 a. Apin 280 is placed beneath an apex portion of the non-optical convexsurface 12 e of the anterior mould part. When the release head 19 islowered over the anterior mould part 12, the annulus 19 a pressesagainst an upwardly facing annular surface 12 f surrounding the mouldingcavity of the anterior mould part thereby causing the free end of thepin 280 to engage with the non-optical convex surface 12 a and deformingthe anterior mould part 12 and breaking the bond between the mould partand the lens, starting from the centre of the lens and continuing tinthe outward direction. A similar tool is described in U.S. Pat. No.6,558,584 (O'Neill et al.) where instead of the annulus 19 a of the '212reference, a specifically configured top plate 580 (FIG. 12) isprovided. During the release process, the pin 280 located underneath theanterior mould part 12 moves towards the mould part 12 and displaces itso that the upwardly facing annular surface 12 f of the anterior mouldpart presses against a downwardly facing flat surface 581 of the topplate 58.

Once the adhesive bond has been broken, the lens is retrieved, forexample by a vacuum picking tool.

When releasing a lens from its associated mould in the dry state, thelens will necessarily absorb some of the force used against the mould torelease the lens therefrom. Thus, as with the previous step of releasingthe posterior mould section from the anterior mould section, the forceused to release the lens from the mould must be of a force strong enoughto break the adhesive bond between the lens and the opposing mouldsurface, yet not so forceful or haphazard that the optical surfaces ofthe lens are harmed by the release process. As with the previous step ofdecapping, should the lens crack or be otherwise damaged during the lensrelease process, the lens must be rejected, thereby lowering the outputyield and increasing manufacturing costs. While the above dry releasemethods are satisfactory in certain mould part/lens combinations ofmaterials and designs, they have proven unsatisfactory in instanceswhere, for example, the mould part is formed of a relatively rigidmaterial which makes it harder to deform the mould part relative to thelens to which it is adhered without harming the lens in the process.This situation is particularly acute when the lens is a toric lens whichincludes indicia in the lens surface which tend to adhere to the mouldpart more strongly than the surrounding smooth surface of the lens.Releasing a lens of this type in the dry state can cause crackingparticularly adjacent the toric markings of the lens. Furthermore, theabove methods are associated with the risk of damaging the edge of thelens.

Consequently, there remains a need in the art for an improved method ofreleasing a lens from its associated mould part while in the dry state.

The object of the present invention is to obviate and/or mitigate theabove discussed problems of the prior art.

Accordingly, the invention provides a device for supporting a mouldcomprised of an anterior mould section, a posterior mould section and acontact lens formed in a mould cavity defined between the mouldsections, the device comprising:

a support post having a longitudinal axis;

a first support element positioned on the post radially outwardly spacedfrom the longitudinal axis, the first support element comprising a firstface for supporting the posterior mould section and a radially inwardlydirected face;

a second support element positioned on the post spaced from the firstsupport element, the second support element comprising a second face forsupporting the anterior mould section and a radially outwardly directedface;

wherein the first and second support elements are configured withrespect to the mould so that when the posterior mould section rests onthe first face, the anterior mould section is longitudinally spacedapart from the second support element.

In order to maintain the longitudinal spacing, the first and secondsupport elements are ideally immovable with respect to each other.

It will be appreciated that in the present application, expressions“longitudinal(ly)”, “longitudinally directed”, “in the longitudinaldirection” etc., “diametrically”, “radially” etc. are used with respectto the longitudinal axis.

In one embodiment, the longitudinal spacing between the posterior mouldsection and the second support element is achieved by sufficientlyspacing apart the first and the second faces along the longitudinal axisso that when the posterior mould section rests on the first face, thesecond face is spaced apart form the anterior mould section.

Preferably, a gap is defined between the radially inwardly directed faceof the first support element and the radially outwardly directed face ofthe second support element, the gap being configured to receive a skirtportion depending from the anterior mould section.

In a preferred arrangement, the gap is configured so as to accommodate aflange projecting from the skirt portion of the anterior mould section,thereby further providing for improved flexibility of the mould.

Ideally, the first end face is adapted to support at least a peripheralportion of a flange projecting from a skirt portion of the posteriormould section.

Such an arrangement provides for greater flexibility of the mouldcompared to the prior art devices. The flexibility of the mould isrequired during the operation of decapping, which will be discussedbelow n greater detail, i.e. separation of the anterior mould sectionfrom the posterior mould section.

Ideally, the second support element is configured with respect to theskirt portion of the anterior mould section so as to be received withinthe skirt portion. More specifically, the second support element ispreferably configured with respect to the skirt portion of the anteriormould section so that when the second support element is received withinthe skirt, a sufficient spacing is provided between inner surfaces ofthe skirt and outer surfaces of the second support element to provide aclearance for deformation of the skirt in the radial direction.

In a most preferred arrangement, the second face is configured to abutan outer convex surface of the anterior mould section. This abutmentoccurs after the posterior and the anterior mould sections have beenseparated from each other and, since the anterior mould section is notsupported by anything, apart from being adhered to the posterior mouldsection, the anterior mould section drops onto the second face. Theanterior mould section drops under the influence of gravity which may beassisted by vacuum. Preferably, the second face is in a form of anannular surface surrounding an aperture formed in the second supportelement such that when the outer convex surface of the posterior mouldsection abuts the annular surface, a portion of the outer convex surfaceprojects into the aperture the aperture being sized and shaped so thatthe outer convex surface remains spaced apart from surfaces defining theaperture. In one aspect, the annular surface serves to support theanterior mould section during the operations of removing the monomerring (i.e. the excess material expelled from the moulding cavity into areservoir between mutually facing surfaces of the mould sectionssurrounding the cured lens) and releasing the lens from the anteriormould section. These operations will be discussed below in greaterdetail. In another aspect, the annular surface serves as a bearingsurface for bending of the anterior mould section during thoseoperations when a longitudinally directed force is applied to the flangeof the skirt of the anterior mould section. In one embodiment, theaperture of the second support element may be in a form of a bore.

In a preferred embodiment, the first support element comprises a pair ofdiametrically opposing shoulders, preferably arcuate, but not limitedthereto. The shoulders ideally project proud from an end surface of thepost in the longitudinal direction. Such an arrangement has theadvantage that the flange of the skirt of the posterior mould section issupported by the shoulders only at diametrically opposing regions of theflange and not along its entire circumference thereby providing for thenecessary freedom to flex for the posterior mould section during thedecapping operation.

Conveniently, each shoulder comprises a slot formed in the radiallyinwardly facing face of the shoulder, the slot being configured toreceive at least a peripheral portion of the flange of the anteriormould section upon radial outward deflection (discussed below) ofadjacent portions of the skirt of the anterior mould section during theoperations of removing the monomer ring and releasing the lens from theanterior mould section. The slot may be either through or blind as longas it is configured to accommodate the deflected flange.

In a preferred embodiment, the second support element and the gapbetween the radially inwardly directed face of the first support elementand the radially outwardly directed face of the second support elementare configured with respect to the anterior mould section so that whenthe anterior mould section rests on the second face, the flange of theskirt of the anterior mould section is suspended within the gap, i.e.does not come into contact with any of the surrounding surfaces. Thisprovides the flange with the necessary freedom to flex during theapplication thereto of the longitudinal force.

In a preferred arrangement, the second support element comprises apillar located substantially centrally between the shoulders. The pillarideally projects proud from the end surface of the post in thelongitudinal direction, i.e. in the same direction as the shoulders. Inone arrangement, the second face may comprise a chamfer formed betweenan end surface of the pillar and an inner surface defining the aperture.Of course, other configurations of the second face are envisaged withinthe scope of the invention, such as for example an annular rounded edge.The pillar preferably comprises a pair of diametrically opposing flatson an outer surface of the pillar so as to provide a clearance forradial inward deformation of the skirt of the anterior mould sectionwhen the anterior mould section rests on the second face. The radialinward deformation occurs during the operations of removing the monomerring and releasing the lens from the anterior mould section when alongitudinal force is applied to a pair of diametrically opposedportions of the flange of the anterior mould section causing adjacentskirt portions to deflect towards the longitudinal axis. The radialinward deformation of these portions at the skirt causes two otherdiametrically opposed portions thereof perpendicular to the first twoportions to deflect radially outwardly, as discussed above.

The post ideally comprises a pair of diametrically opposing flats on anouter surface of the post to prevent rotation of the post in a pallet.Other known means for preventing rotation of the post are alsoenvisaged.

The present invention further provides a pressing means for applying alongitudinally directed force to a central area of an outer concavesurface of the posterior mould section when the posterior mould sectionand, in particular, the flange thereof rests on the first face, thelongitudinally directed force being sufficient to compress and deformthe posterior mould section between the means and the first face therebybreaking an adhesive bond between the lens and the posterior mouldsection, starting around peripheral regions of the lens and continuingtowards the centre of the lens. In this manner, the posterior section is“peeled” away from the lens so that the mould sections separate fromeach other. The posterior mould section can then be taken away, whilstthe lens and the surrounding monomer ring remain adhered to the anteriormould section. It has been found that in this arrangement, only afraction of the force is required to separate the mould sectionscompared to the known prior art methods.

In one embodiment, the pressing means may comprise a pin. The pin has afree end which is preferably of a rounded shape. In use, the free end ofthe pin applies pressure to the outer concave surface of the posteriormould section during the decapping operation. The pin may be movable andthe support post may remain stationary. However, it is within the scopeof the present invention to arrange the pin to remain stationary and thepost to be movable. Indeed, both the pin and the post may be movablymounted.

Yet further, the present invention provides a first means for supplyingat least one jet of gas directed at an interface between a rim of excessexpelled lens material (i.e. the monomer ring) formed around peripheralregions of the lens and adhered to a surface of the anterior mouldsection surrounding the lens, the force of the jet being sufficient tobreak the adhesive bond between the excess lens material and the surfaceand thereby to separate the excess lens material from the anterior mouldsection.

The means for supplying the at least one jet of gas may comprise a firstelement positionable about the excess lens material, the first elementcomprising a channel for supplying the gas and forming the at least onejet. In a preferred arrangement, the first element comprises asubstantially tubular wall having an inner surface, and the gas supplychannel comprises an aperture formed in the inner surface of the tubularwall, the aperture being located so that when the first element isbrought into a pre-determined position about the excess material, theaperture is positioned substantially opposite the interface. Ideally,the first element comprises a plurality of apertures spaced around theperimeter of the inner surface of the tubular wall. In one specificarrangement, the inner surface is cylindrical and the first elementcomprises eight apertures spaced at 45° from each other.

In addition, the means for supplying the at least on jet of gas maycomprise a vacuum means longitudinally spaced apart from the gaschannel, the vacuum means being operable to draw the gas away from themould section. The vacuum force may be selected sufficient to take theremoved monomer ring away from the posterior mould section.

Still further, the present invention provides a second means forapplying a longitudinally directed force to the flange of the skirt ofthe anterior mould section, when the anterior mould section rests on thesecond face. In one application, this force is sufficient to cause asurface of the anterior mould section surrounding the lens to whichsurface excess lens material formed around peripheral regions of thelens is adhered to deflect in the direction of the force thereby atleast partially breaking the adhesive bond between a rim of excessexpelled lens material and the surface. In another application, theforce is sufficient to cause a concave surface of the anterior mouldsection to which the cured lens is adhered to deflect in the directionof the force thereby breaking the adhesive bond between the lens and theconcave surface of the posterior mould section at least aroundperipheral regions of the lens starting from an outer edge of the lensand continuing in the direction of the centre of the lens. In thismanner, peripheral regions of the lens are firstly separated or “peeled”from the anterior mould section before the lens is subjected to anoperation of releasing the entire lens from the anterior mould section.This ensures that the edge of the lens remains intact during theoperation of releasing the entire lens. Upon separating the peripheralregions of the lens, the anterior mould section together with the lens,may be transferred to another location for releasing the entire lens.The second means for applying the longitudinally directed force to theflange of the anterior mould section ideally comprise a pair ofdiametrically spaced apart projections, each projection comprising anend face adapted for abutting and pressing against the flange. In suchan arrangement, the force is applied only to a pair of diametricallyopposing regions of the flange, thereby providing the flange and theskirt with the necessary freedom to flex radially inwardly under thepressure applied by the projections. At the same time, another pair ofdiametrically opposing regions perpendicular to the first two regionsdeflect radially outwardly.

-   -   In one arrangement, the first and second means are preferably        connected to each other so that when the first means is brought        into the pre-determined position about the excess material in        order to apply the at least one jet of gas, the second means        applies the longitudinally directed force to the flange of the        anterior mould section.

In a further aspect, the invention provides a method of separating theposterior mould section from the anterior mould section and from thecured lens formed in the mould cavity defined between the mouldsections, wherein the lens is adhered to corresponding moulding surfacesof the mould sections, the method comprising the steps of:

-   -   locating at least a peripheral portion of the flange of the        posterior mould section on the first face of the first support        element; and    -   applying a substantially longitudinally directed force to the        central area of the outer concave surface of the posterior mould        section, the force being sufficient to compress and deform the        posterior mould section between the area of application of the        force and the first face thereby breaking an adhesive bond        between the lens and the posterior mould section, starting        around peripheral regions of the lens and continuing towards the        centre of the lens, whereby the posterior mould section        separates or “peels” away from the anterior mould section and        the lens remains adhered the inner concave surface of the        anterior mould section.

Applying the longitudinally directed force to the central area of theouter concave surface of the posterior mould section preferably includespressing the above described pin against the central area.

The application of the force also causes the excess cured lens material(the monomer ring) formed around peripheral regions of the lens andadhered to surfaces of the mould sections surrounding the lens toseparate from the posterior mould section and remain adhered to theanterior mould section.

In a preferred arrangement, when the flange of the posterior mouldsection is located on the first support element, the flange of theanterior mould section is received in the gap defined between theradially inwardly facing face of the first support element and theradially outwardly facing face of a second support element. The firstand second elements are configured with respect to the anterior mouldsection so that the latter is longitudinally spaced apart from thesecond support element. The anterior mould section does not come intocontact with any of the surrounding surfaces and is held only by theadhesive bond between the anterior mould section and the lens, whichlens in turn is adhered to the posterior mould section. Consequently,upon separation of the posterior mould section from the anterior mouldsection and from the lens, the anterior mould section drops onto thesecond face of the second support element whereby the second face comesinto abutment with the outer convex surface of the anterior mouldsection, as described above.

In yet a further aspect, the invention provides a method of removingexcess expelled cured lens material adhered to a surface of the anteriormould section surrounding the lens, the excess material being formedaround peripheral regions of the cured lens, the cured lens beingadhered to the concave moulding surface of the mould section, the methodcomprising the steps of:

-   -   locating the anterior mould section on the second support        element; and    -   directing at least one jet of gas at the interface between the        excess lens material and the surface of the mould section to        which the excess material is adhered, the force of the at least        one jet being sufficient to break the adhesive bond between the        mould section and the excess lens material and to separate the        excess lens material from the mould section.

Ideally, a first element is positioned about the excess lens material,the first element comprising a channel for supplying and forming the atleast one jet of gas, so that the channel is positioned substantiallyopposite the interface.

In a preferred arrangement, the method comprises directing a pluralityof jets of gas supplied from a plurality of channels spaced apart fromeach other on the first element so as to at least partially, andpreferably wholly, encompass the excess material.

Ideally, the jets of gas are supplied from the eight apertures spaced at45° from each other along the perimeter of the inner surface of thetubular wall of the first element.

The gas is preferably drawn away from the mould section (using e.g.vacuum) thereby carrying the separated excess material away from themould section.

Ideally, the method comprises locating the outer convex surface of theanterior mould section on the annular surface of the second supportelement.

In order to assist the jet(s) of gas in removing excess material, alongitudinally directed force is preferably applied to the flange of theanterior mould section, the force being sufficient to cause the surfaceof the anterior mould section to which the excess expelled cured lensmaterial is adhered to deflect in the direction of application of theforce thereby at least partially breaking the adhesive bond betweenperipheral regions of the excess expelled cured lens material and theposterior mould section and thereby assisting the gas jets in enteringthe interface. Ideally, the longitudinal force is applied by the pair ofdiametrically opposed projections.

In a preferred arrangement, upon removing the excess material from theanterior mould section, the longitudinally directed force continues toapply to the flange. This force is sufficient to cause the inner concavesurface of the anterior mould to deflect in the direction of theapplication of the force thereby breaking the adhesive bond between thelens and the surface, at least around peripheral regions of the lens,starting from an outer edge of the lens and continuing in the directionof the centre of the lens.

DESCRIPTION OF SPECIFIC EMBODIMENTS

The invention will hereinafter be more particularly described withreference to the accompanying drawings which show, by way of exampleonly, an embodiment of the present invention.

In the drawings:

FIGS. 1 and 2 show cross-sectional views of a prior art mould for castmoulding a lens;

FIG. 3 illustrates a prior art method of separating the mould parts of acast mould from each other so that the cured lens remains adhered to oneof the mould parts;

FIGS. 4 and 5 are cross-sectional views of a prior art mould for castmoulding a lens illustrating the process of moulding a lens and theformation of a “monomer ring” around the lens;

FIGS. 6 to 8 are enlarged views of the mould of FIGS. 4 and 5 showingthe steps of lens cure, mould separation and lens and monomer ringrelease, respectively;

FIG. 9 is a cross-sectional view of a prior art mould with a cured lenstherein showing a prior art arrangement for removing the “monomer ring”;

FIGS. 10 to 12 each shows a cross-sectional view of a prior art devicefor dry-releasing a cured lens from a surface of a mould section.

FIG. 13 is a perspective view of a device according to the invention forsupporting a mould with a lens.

FIGS. 14 and 15 are a side cross-sectional view and a top view,respectively of the post of FIG. 13;

FIG. 16 is a side elevation of an assembly in accordance with theinvention for separating an anterior mould section from a posteriormould section;

FIG. 17 is a side elevation of an assembly in accordance with theinvention for removing excess material and releasing edges of the curedlens from the posterior mould section; and

FIG. 18 is a schematic illustration of a force measurement system foruse with the present invention.

The invention is illustrated in FIGS. 13 to 17. With reference initiallyto FIGS. 13 to 16, an assembly for separating a posterior mould sectionfrom an anterior mould section will be described.

FIG. 16 shows a typical mould 2 for cast moulding an ophthalmic lens.The mould 2 comprises a posterior mould section 21 for forming theposterior, i.e. the concave lens surface and an anterior mould section22 for forming the anterior, i.e. the convex lens surface. The mouldsections 21 and 22 include respective tubular skirts 23 and 24. Theinner diameter of the skirt 23 is larger than the outer diameter of theskirt 24 so that the skirt 24 can be received in the skirt 23. Eachskirt 23 and 24 has a radially projecting flange 20 and 200,respectively. Each flange 20, 200 has and end face 20 a and 200 a,respectively and a back face 20 b, 200 b, respectively. A gap 25 isdefined between the inner and outer surfaces of the skirts 23 and 24,respectively, to provide a clearance to enable the outer skirt 23 toflex as will be described below.

In FIG. 16, the mould 2 is shown with a lens 10 having already beenformed (in accordance with a typical moulding process described above)and cured between an inner convex surface 27 of the posterior mouldsection 21 and an inner concave surface 26 of the anterior mould section22. A gap 28 is defined between annular surfaces 21 c and 22 c of theposterior and anterior mould sections, respectively, surrounding theirrespective surfaces 27 and 26. The gap 28 serves as a reservoir forreceiving excess lens material expelled from the mould cavity during theformation of the lens 10. The excess material 11 is typically referredto in the art as “monomer ring”. After the lens 10 has been cured, themould sections 21, 22 need to be separated from each other. Thisoperation is typically referred to in the art as “decapping”.

Separation of Mould Parts

FIG. 16 illustrates an assembly according to the invention for decappingthe mould 2. The assembly comprises a support post 30 on which the mould2 is located. The post 30 is preferably, but without any limitation tothe scope of the invention, adapted to be placed on a pallet (not shown)for carrying a plurality of such supporting posts. With reference toFIGS. 13 to 15, the support post 30 comprises a longitudinal axis 32 anda first supporting element in the form of a pair of opposing shoulders31 radially outwardly spaced from the longitudinal axis 32. Herein,expressions “longitudinal(ly)”, “longitudinally directed”, “in thelongitudinal direction” etc., “diametrically”, “radially” etc. should beunderstood to be used in relation to the longitudinal axis 32. Eachshoulder 31 projects proud from a base face 38 of the post 30 and has afirst end face 31 a and an inwardly radially facing face 31 b. The post30 also comprises a second supporting element in the form of a pillar 33located substantially centrally between the shoulders 31 and projectingproud from the base face 38 of the post 30. The pillar 33 has a secondend face 33 a and a radially outwardly facing face 33 b. In the presentembodiment, the shoulders 31 and the pillar 33 are parts of the sameelement. It is within the scope of the invention that separate posts maybe provided, one for supporting the posterior mould section 21 and theother for supporting the anterior mould section 22. Also, the supportingpost 30 and shoulders 31 are immovable with respect to one another.Nevertheless, other arrangements are envisaged within the scope of theinvention in which the shoulders 31 can be movably arranged with respectto the pillar 33. As seen from FIG. 13, the shoulders 31 in thepresently described embodiment are arcuate and the pillar 33 is in theform of a substantially cylindrical tube. The invention, however, is notlimited to these particular configurations. A gap 34 is defined by theinwardly facing face 31 b of each shoulder 31, the outwardly facing face33 b of the pillar 33 and the base face 38 of the post. When the mould 2is mounted on the post 30, peripheral portions of the flange 20 of theposterior mould section 21 rest on the first end faces 31 a. At the sametime, a portion of the skirt 24, together with the flange 200 of theanterior mould section 22 are received in the gap 34. The dimensions ofthe shoulders 31, the pillar 33 and the gap 34 are selected with respectto the mould 2 such that when the flange 20 rests on the first end faces31 a, an outer face 22 a of the anterior mould section surrounding thecurved (i.e. the mould cavity forming) portion 290 of the anterior mouldsection and the second end face 33 a are spaced apart. In fact, theanterior mould section 22 does not come into contact with any of thesurrounding surfaces, except the anterior lens surface to which it isadhered. This spacing provides the outer skirt 23 with freedom to flexduring the decapping operation. In the present embodiment, the pillar 33comprises a tubular wall 33 e which has an inner surface 33 f whichdefines an inner bore 33 c. The inner bore 33 c is sized and shaped soas to at least partially accommodate the curved portion 290 of theanterior mould section 22. It will be appreciated that instead of thebore 33 c e.g. a suitably shaped blind recess may be provided. If thepost 30 is to be used in a pallet for handling a plurality of suchposts, a pair of diametrically opposing flats 35 may be provided on theouter surface of the post 30 to prevent rotation of the post in thepallet. Various other means usual in the art may alternatively beprovided for securing the post 30 in the pallet.

Referring to FIG. 16, the decapping assembly further comprises a pin 40positionable against an outer concave surface 29 a of the curved (i.e.the mould cavity forming) portion 29 of the posterior mould section 21.The pin 40 has a rounded free end 40 a to enable a surface contactbetween the free end 40 a and a central region of the outer concavesurface 29 a. It will be appreciated that the scope of the invention isnot limited to such a particular rounded configuration of the pin end 40a. In the present embodiment, the pin 40 is movable and the post 30remains stationary. However, it is possible to arrange the assembly sothat the post 30 is movable and the pin 40 remains stationary, or sothat both the pin 40 and the post 30 can be moved relative to eachother.

In use, during the decapping operation, the free end 40 a of the pin 40applies a longitudinally directed force to the central portion of theouter concave surface 29 a. The first end faces 31 a of the shoulders 31apply a counteractive force against the end face 20 a of the flange 20of the posterior mould section 21. Consequently, the mould 2 iscompressed between the free end 40 a of the pin 40 and the first endfaces 31 a of the shoulders 31. The compression force deforms the curvedpart 29 of the posterior mould section and breaks the adhesive bondbetween the lens-forming convex surface 27 of the posterior mouldsection 21 and the concave posterior surface of the lens 10. Theadhesive bond starts to break initially at the periphery of the lens 10and continues to break towards the centre of the lens. The posteriormould section 21 thereby “peels” away or separates from the lens andfrom the anterior mould section 22 so that the lens 10 remains adheredto the lens-forming concave surface 26 of the anterior mould section 22.The monomer ring 11 remains adhered to an annular surface 22 c of theanterior mould section 22 surrounding the lens-forming concave surface26. The separated posterior mould section 21 can then be taken away bysuitable instrument such as a vacuum picker or a gripping tool.

Once the mould sections 21 and 22 have been separated, the anteriormould section 22 (since it is only held by the adhesive bond with thelens 10) falls under the influence of gravity onto the pillar 33 so thata region of an outer convex surface 290 a of the curved portion 290abuts an annular surface or a chamfer 33 d formed between the second endface 33 a of the pillar 33 and the inner surface 33 f therebypositioning the posterior mould section 22 for the subsequent operationsof removing the monomer ring 11 and releasing the lens 10 from theposterior mould section 22. Only an annular region of the outer convexsurface 290 a abuts the chamfer 33 d. The remaining portion of theconvex surface 290 a surrounded by the chamfer 33 d projects into thebore 33 c. It will be appreciated that instead of the chamfer 33 d, asquare, rounded or otherwise suitably shaped edge (not shown) may beprovided. The outer diameter of the pillar 33 is sufficiently smallerthan the inner diameter of the skirt 24 firstly, to enable asubstantially snug-free advancement of the anterior mould section 22towards the pillar 33 and secondly, to allow the anterior mould section22 to flex during the operations of removing the monomer ring 11 andreleasing the lens 10 from the anterior mould section 22, which will bedescribed below.

It is believed that the above described configuration of the post withrespect to the mould 2 helps to reduce the force required to separatethe mould sections 21, 22 so as to provide for more gentle separationand to reduce the risk of so called “edge defects”, i.e. damage to theperipheral portions of the lens 10.

Removing the Monomer Ring and Releasing an Outer Edge of the Lens

With reference to FIGS. 13 to 15 and 17, an assembly for removing themonomer ring 11 and releasing peripheral regions about the outer edge ofthe lens 10 from the anterior mould section 22 will now be described.

As shown in FIG. 17, the monomer ring removing and lens edge releasingassembly comprises the above-described supporting post 30. The pillar 33and the shoulders 31 are sized and configured with respect to theanterior mould section 22 so that when the convex surface 290 a of theanterior mould section 22 rests on the chamfer 33 d, the end face 200 aof the flange 200 is spaced sufficiently apart from the surroundingsurfaces, in particular the base face 38, so as to enable the flange 200to flex upon application thereto of a longitudinally directed force aswill be described below. Also, whilst the convex surface 290 a abuts thechamfer 33 d, the outer face 22 a and the second end face 33 a remainspaced apart. This latter arrangement allows the anterior mould section22 to flex about the annular region of contact between the chamfer 33 dand the convex surface 290 a.

The assembly further comprises a collar unit 50 which in use ispositioned adjacent the anterior mould section 22. The collar unit 50comprises a substantially tubular wall 51 an inner surface 51 a of whichdefines an inner bore 51 b. When the collar unit 50 is positionedadjacent the anterior mould section 22, the wall 51 encompasses thelens-forming concave surface 26 of the posterior mould section 22together with the lens 10 and with the monomer ring 11 around the lens10. A number of gas supply apertures 53 are formed in an inner surface51 c of the wall 51. The gas supply apertures 53 are located on theinner surface 51 a so that when the collar unit 50 is brought into apredetermined position adjacent the anterior mould section 22, theapertures 53 are positioned substantially opposite the interface 100 andpreferably substantially level with the outer annular surface 22 c. Eachaperture 53 is configured to shape gas passing therethrough into a jetand to direct the jet at an interface 100 between the outer annularsurface 22 c and the monomer ring 11. The apertures may, however, bealso located above or/and below the level of the annular surface 22 c aslong as the jets of gas are directed at the interface 100. Thearrangement is configured such that the force applied by the jets of gasis sufficient to break the bond between the monomer ring 11 and theannular surface 22 c and to lift and remove the monomer ring 11 from theannular surface 22 c. In the present embodiment, eight apertures 53circumferentially spaced from each other by 45° have been foundsufficient. It will be appreciated that the invention is not limited tothe plurality of the gas supply apertures 53. Instead, for example, asingle circumferentially extending slot (not shown) can be formed in theinner surface 51 a. An example of gas to be used for the monomer ringremoval is air, but it will be appreciated that that other inert gas ofgaseous mixture can be utilised.

In the present embodiment, the collar unit 50 has an end member 52 forapplying a longitudinally directed force to the back surface 200 b ofthe flange 200. In the present embodiment, the collar unit 50, as willbe described below, is used for both removing the monomer ring 11 andfor releasing peripheral regions about the edge of the lens 10 from theposterior mould section 22, but it will be appreciated that the collarunit 50 and the end member 52 may be provided as separate attachmentsfor these two operations. The end member 52 comprises a pair ofdiametrically opposing projections 52 a. At the same time when thecollar unit is brought into the predetermined position adjacent theanterior mould section for the application of the gas jets, theprojections 52 a press against the back surface 200 b of the flange 200.Under the force of the projections 52 a, the portions of the flange 200(together with the adjacent skirt 24 portions) which are in contact withthe projections 52 a deform and deflect substantially radially inwardly.The chamfer 33 d of the pillar 33 applies a counteractive force againstthe outer convex surface 290 a of the anterior mould section 22 causingthe concave portion 290 and the outer surface 22 c to bend about theregion of contact between the convex surface 290 a and the chamfer 33 d.This deformation causes the outer annular surface 22 c to deflect in thedirection of application of the force by the projections 52 a therebybreaking the adhesive bond between the monomer ring 11 and the outerannular surface 22 c. Peripheral regions of the monomer ring 11 thuspeel off and stand proud on the annular surface 22 c so that a space(not shown) is created therebetween. When the gas jets are activated,they enter the space created between the monomer ring 11 and the annularsurface 22 c and separate the remaining portions of monomer ring 11 fromthe annular surface 22 c.

The above described radial inward deflection of the flange 200 and theskirt 24 causes the other portions of the flange 200 (and the adjacentskirt 24 portions) which are not in contact with the projections 52 a todeflect substantially radially outwardly. If the opposing projections 52a are so located with respect to the post 30 that they contact thoseportions of the flange 200 which are disposed outside the gap 34, thoseportions of the flange 200 which are disposed inside the gap 34 willdeflect radially outwardly and would interfere with the shoulders 31.For this reason, each shoulder 31 has a slot 36 which can either bethrough as shown in FIG. 14 or blind (not shown). The slot is sized andshaped for accommodating the radially outwardly deflecting flange 200and a portion of the skirt 24. Also, in order to provide more room forthe deformation of the flange 200 and the skirt 24, a pair ofdiametrically opposing flats 37 may be provided on the outer surface ofthe pillar 33.

Once the monomer ring 11 has been separated from the posterior mouldsection 21, it is taken away from the mould by suitable means such as,for example, vacuum or gripping means. For example only, as shown inFIG. 17, vacuum apertures 55 may be provided in the inner surface 51 aof the wall 51 longitudinally spaced apart from the anterior mouldsection 22. The size of the vacuum apertures 55 is sufficient to allowthe separated monomer ring 11 to pass therethrough away from theanterior mould section 22 area.

Next, the peripheral regions about the edge of the lens 10 have to bereleased from the anterior mould section 22. For this purpose, theprojections 52 a continue to apply the force against the back surface200 b of the flange 200 in the same manner as described above inconnection with the removal of the monomer ring 11 thereby breaking theadhesive bond between the lens and the concave surface 26 startingbetween the outer edge of the lens 10 and the lens-forming concavesurface 26 and continuing towards the centre of the lens 10, therebyreleasing peripheral regions from the anterior mould section. Uponseparation of the peripheral regions of the lens, the anterior mouldsection together with the pre-separated lens is ready to be subjected toa known operation of separation of the entire lens from the anteriormould section. In this manner, the risk of damage to the lens edgeduring the release of the lens is greatly reduced compared to knownmethods.

Once released, depending on the design of the manufacturing process, thelens 10 may be removed by a suitable tool, such as for example, a vacuumpicker. Alternatively, the lens 10 may remain in the mould cavity and betransferred together with the post 30 to downstream locations. It isbelieved that the above described assembly and method of removing themonomer ring 11 and releasing the lens 10 significantly help to reducethe risk of damaging the outer edges of the lens 10. Such damage to theouter edge of the lens is a serious defect which leads to the lenshaving to be rejected by quality control and discarded.

In the above described assembly for removing the monomer ring andreleasing the lens edge, the collar unit 50 is movable and the post 30remains stationary. However, it is possible to arrange the assembly sothat the post 30 is movable and the collar unit 50 remains stationary,or so that both the collar unit 50 and the post 30 can be moved to andfrom each other. Also, in the present embodiment, the above describedassembly is suitable for both removing the monomer ring 11 and releasingthe lens edge. Although such a combined assembly is highly advantageousand convenient, since it provides for the reduction of manufacturingtime, it will be appreciated that the invention is not limited to thecombined assembly. For example, instead, two separate assemblies can beprovided, one assembly for removing the monomer ring 11 and the otherassembly for releasing the lens edge. Accordingly, the first assemblymay comprise the post 30 and the above described collar unit 50 togetherwith the end member 52. The second assembly may comprise the post 30 andjust the end member 52 for the operation of releasing the lens edge.

For a successful decapping operation, an optimal force should to beselected to be applied by the pin 40 to the outer concave surface 29 aof the posterior mould section 21. Similarly, an optimal force should beselected to be applied by the opposing projections 52 a to the flange200 of the anterior mould section 22 in order to remove the monomer ring11 and release the lens edge. Incorrectly selected forces may causedamage to the lens. For the purpose of determining optimal forces to beapplied by the pin 40 and by the projections 52 a, a force measurementsystem 60 schematically shown in FIG. 18 has been designed. The system60 comprises an interchangeable head 61 connected to either amechanically driven load cell 62 or a servo (not shown). Theinterchangeable head 16 can be used with the pin 40 to measure anoptimal force for decapping, and with the projections 52 a to measurethe optimal force for removing the monomer ring 11 and releasing thelens edge. The system also comprises a means for supporting the mouldsections 21, 22 during the measurements which may take the form of apallet 62. The pallet 62 is supplied with interchangeable fixtures 63(one fixture only is shown in FIG. 18) for placement of mould sections21, 22 for the respective operations decapping and removing monomer ring11/releasing the lens edge. The interchangeable fixture 63 is positionedunderneath the interchangeable head 31 so that, when received in theinterchangeable fixture, the centre of the relevant mould section 21 or22 is aligned with the interchangeable head. By operating theinterchangeable head 61 with different force settings, optimum force isestablished for the operations of decapping and removing monomer ring11/releasing the lens edge.

It will of course be understood that the invention is not limited to thespecific details described herein, which are given by way of exampleonly, and that various modifications and alterations are possible withinthe scope of the invention.

1. A device for supporting a mold comprised of an anterior mold section,a posterior mold section and a contact lens formed in a mold cavitydefined between the mold sections, the device comprising: a support posthaving a longitudinal axis; a first support element positioned on thepost radially outwardly spaced from the longitudinal axis, the firstsupport element comprising a first face for supporting the posteriormold section, and a radially inwardly directed face; a second supportelement positioned on the post spaced from the first support element,the second support element comprising a second face for supporting theanterior mold section, and a radially outwardly directed face; whereinthe first and second support elements are configured with respect to themold so that when the posterior mold section rests on the first face,the anterior mold section is longitudinally spaced apart from the secondsupport element; and wherein the first and second support elements areimmovable with respect to each other.
 2. A device as claimed in claim 1,wherein a gap is defined between the radially inwardly directed face ofthe first support element and the radially outwardly directed face ofthe second support element, the gap being configured to receive a skirtportion depending from the anterior mold section.
 3. A device as claimedin claim 1, wherein the gap is configured so as to accommodate a flangeprojecting from the skirt portion of the anterior mold section.
 4. Adevice as claimed in claim 1, wherein the first face is adapted tosupport at least a peripheral portion of a flange projecting from askirt portion of the posterior mold section.
 5. A device as claimed inclaim 1, wherein the first and second faces are spaced from each otheralong the longitudinal axis so that when the posterior mold sectionrests on the first face, the second face is spaced apart form theanterior mold section.
 6. A device as claimed in claim 1 wherein thesecond support element is configured with respect to the skirt portionof the anterior mold section so as to be received within the skirtportion.
 7. A device as claimed in claim 1 wherein the second supportelement is configured with respect to the skirt portion of the anteriormold section so that when the second support element is received withinthe skirt, sufficient spacing is provided between inner surfaces of theskirt and outer surfaces of the second support element to provideclearance for deformation of the skirt in the radial direction.
 8. Adevice as claimed in claim 7 wherein the second face is configured toabut an outer convex surface of the anterior mold section.
 9. A deviceas claimed in claim 8 wherein the second face is in a form of an annularsurface surrounding an aperture formed in the second support elementsuch that when the outer convex surface of the anterior mold sectionabuts the annular surface, a portion of the outer convex surfaceprojects into the aperture, the aperture being sized and shaped so thatthe outer convex surface remains spaced apart from surfaces defining theaperture.
 10. A device as claimed in claim 9, wherein the aperture ofthe second support element is in a form of a bore.
 11. A device asclaimed in claim 1, wherein the first support element comprises of apair of diametrically opposing shoulders.
 12. A device as claimed inclaim 11, wherein the shoulders are arcuate.
 13. A device as claimed inclaim 12, wherein each shoulder comprises a slot formed in the radiallyinwardly facing face, the slot being configured to receive at least aperipheral portion of the flange of the anterior mold section when theanterior mold section rests on the second face upon radial outwarddeflection of adjacent portions of the skirt of the anterior moldsection.
 14. A device as claimed in claim 13, wherein the second supportelement comprises of a pillar located substantially centrally betweenthe shoulders.
 15. A device as claimed in claim 14, wherein the secondface comprises a chamfer formed between an end surface of the pillar andan inner surface defining the aperture.
 16. A device as claimed in claim15, wherein the pillar comprises a pair of diametrically opposing flatson an outer surface of the pillar so as to provide a clearance forradial inward deformation of the skirt of the anterior mold section whenthe anterior mold section rests on the second face.
 17. A device asclaimed in claim 1, wherein the post comprises a pair of diametricallyopposing flats on an outer surface of the post to prevent rotation ofthe post in a pallet.
 18. A device as claimed in claim 1, wherein thesecond support element and the gap between the radially inwardlydirected face of the first support element and the radially outwardlydirected face of the second support element are configured with respectto the anterior mold section so that when the anterior mold sectionrests on the second face, the flange of the skirt of the anterior moldsection is suspended within the gap.
 19. A device as claimed in claim 1,comprising a pressing means for applying a longitudinally directed forceto a central area of an outer concave surface of the posterior moldsection when the posterior mold section rests on the first face, thelongitudinally directed force being sufficient to compress and deformthe posterior mold section between the means and the first face therebybreaking an adhesive bond between the lens and the posterior moldsection, starting around peripheral regions of the lens and continuingtowards the center of the lens, and thereby separating the posteriormold section from the anterior mold section.
 20. A device as claimed inclaim 19, wherein the pressing means comprises a pin having a free end.21. A device as claimed in claim 20, wherein the free end is rounded.22. A device as claimed in claim 21, wherein the pin is movable and thesupport post remains stationary.
 23. A device as claimed in claim 1,comprising a means for supplying at least one jet of gas directed at aninterface between a rim of excess expelled lens material formed aroundperipheral regions of the lens and adhered to a surface of the anteriormold section surrounding the lens, the force of the jet being sufficientto break the adhesive bond between the excess lens material and thesurface and thereby separate the excess lens material from the moldsection.
 24. A device as claimed in claim 1, comprising means forapplying a longitudinally directed force to a radially extending flangeof the skirt of the anterior mold section, when the anterior moldsection rests on the second face.
 25. A device as claimed in claim 24,adapted to apply a force sufficient to cause a surface of the anteriormold section surrounding the lens to deflect in the direction of theforce thereby at least partially breaking an adhesive bond between a rimof excess expelled lens material and the surface.
 26. A device asclaimed in claim 24, adapted to apply a force sufficient to cause aconcave surface of the anterior mold section to which the cured lens isadhered to deflect in the direction of the force thereby breaking theadhesive bond between the lens and the concave surface at least aboutperipheral regions of the lens, starting from an outer edge of the lensand continuing in the direction of the center of the lens.
 27. A devicefor separating a posterior mold section from an anterior mold sectionwherein a cured lens is adhered to corresponding molding surfaces of themold sections, the device comprising: a support post having alongitudinal axis; a first support element positioned on the postradially outwardly spaced from the longitudinal axis, the outer supportelement comprising a first face adapted to provide support for at leasta peripheral portion of a flange projecting from a skirt portion of theposterior mold section; a pressing means for applying a longitudinallydirected force to a central area of an outer concave surface of theposterior mold section, when the flange of posterior mold section restson the first face; the longitudinally directed force being sufficient tocompress and deform the posterior mold section between the pressingmeans and the first face thereby breaking an adhesive bond between thelens and the posterior mold section, starting around peripheral regionsof the lens and continuing towards the center of the lens, therebyseparating the posterior mold section from the anterior mold section.28. A device as claimed in claim 27, wherein the pressing meanscomprises a pin having a free end.
 29. A device as claimed in claim 28,wherein the pin is movable and the support post remains stationary. 30.A device as claimed in claim 29, wherein the first support elementcomprises a radially inwardly directed face and wherein the devicefurther comprises: a second support element positioned substantiallycentrally on the post, the second support element comprising a secondface for supporting the anterior mold section, and a radially outwardlydirected face; a gap defined between the radially inwardly facing faceof the first support element and the radially outwardly directed face ofthe second support element, the gap being configured to receive a skirtportion depending from the anterior mold section; and wherein the firstand second support elements are configured with respect to the mold sothat when the posterior mold section rests on the first face, theanterior mold section is longitudinally spaced apart from the secondsupport element.
 31. A device as claimed in claim 30, wherein the firstand second faces are spaced from each other along the longitudinal axisso that when the posterior mold section rests on the first face, thesecond face is spaced apart to the anterior mold section.
 32. A deviceas claimed in claim 31, wherein the first and second support elementsare immovable with respect to each other.
 33. A device as claimed inclaim 32, wherein the gap is configured so as to accommodate a flangeprojecting from the skirt portion of the anterior mold section.
 34. Adevice as claimed in claim 33, wherein the second support element isconfigured with respect to the skirt portion of the anterior moldsection so as to be received within the skirt portion.
 35. A device asclaimed in claim 34, wherein the second support element is configuredwith respect to the skirt portion of the anterior mold section so thatwhen the second support element is received within the skirt, sufficientspacing is provided between inner surfaces of the skirt and outersurfaces of the second support element to provide clearance fordeformation of the skirt in the radial direction.
 36. A device asclaimed in claim 35, wherein the second face is configured to abut anouter convex surface of the anterior mold section.
 37. A device asclaimed in claim 36, wherein the second face is in a form of an annularsurface surrounding an aperture formed in the second support elementsuch that when the outer convex surface of the anterior mold sectionabuts the annular surface, a portion of the outer convex surfaceprojects into the aperture, the aperture being sized and shaped so thatthe outer convex surface remains spaced apart from surfaces defining theaperture.
 38. A device as claimed in claim 37, wherein the aperture ofthe second support element is in a form of a bore.
 39. A device asclaimed in claim 38, wherein the first support element comprises a pairof diametrically opposing shoulders.
 40. A device as claimed in claim39, wherein the shoulders are arcuate.
 41. A device as claimed in claim40, wherein each shoulder comprises a slot formed in the radiallyinwardly directed face, the slot being configured to receive at least aperipheral portion of the flange of the anterior mold section when theanterior mold section rests on the second face upon radial outwarddeflection of adjacent portions of the skirt of the anterior moldsection.
 42. A device as claimed in claim 41, wherein the second supportelement comprises of a pillar located substantially centrally betweenthe shoulders.
 43. A device as claimed in claim 42, wherein the secondface comprises a chamfer formed between an end surface of the pillar andan inner surface defining the aperture.
 44. A device as claimed in claim43, wherein the pillar comprises a pair of diametrically opposing flatson an outer surface of the pillar so as to provide a clearance forradial inward deformation of the skirt of the anterior mold section whenthe anterior mold section rests on the second face.
 45. A device asclaimed in claim 44, wherein the second support element and the gapbetween the radially inwardly directed face of the first support elementand the radially outwardly directed face of the second support elementare configured with respect to the anterior mold section so that whenthe anterior mold section rests on the second face, the flange of theskirt of the anterior mold section is suspended within the gap.
 46. Adevice as claimed in claim 45, comprising a means for supplying at leastone jet of gas directed at an interface between a rim of excess expelledlens material formed around peripheral regions of the lens and adheredto a surface of the anterior mold section surrounding the lens, theforce of the jet being sufficient to break the adhesive bond between theexcess lens material and the surface and thereby separate this excessmaterial from the mold section.
 47. A device as claimed in claim 46,comprising a pressing means for applying a longitudinally directed forceto a radially extending flange of the skirt of the anterior moldsection, when the anterior mold section rests on the second face.
 48. Adevice as claimed in claim 47, adapted to apply a force sufficient tocause a surface of the anterior mold section surrounding the lens todeflect in the direction of the force thereby at least partiallybreaking an adhesive bond between the excess lens material and thesurface.
 49. A device as claimed in claim 47, wherein the force issufficient to cause a concave surface of the anterior mold section towhich the cured lens is adhered to deflect in the direction of the forcethereby breaking the adhesive bond between the lens and the concavesurface at least about peripheral regions of the lens, starting from anouter edge of the lens and continuing in the direction of the center ofthe lens.
 50. A method of separating an anterior mold section from aposterior mold section and from a cured lens formed in a mold cavitydefined between the mold sections, wherein the lens is adhered tocorresponding molding surfaces of the mold sections, the methodcomprising the steps of: a) providing a support post having alongitudinal axis and a first support element positioned on the postradially outwardly spaced from the longitudinal axis, the outer supportelement comprising a first face adapted to provide support for at leasta peripheral portion of a flange projecting from a skirt portion of theposterior mold section; b) locating at least a peripheral portion of theflange on the first face; and c) applying a substantially longitudinallydirected force to a central area of an outer concave surface of theposterior mold section, the force being sufficient to compress anddeform the posterior mold section between the area of application of theforce and the first face thereby breaking an adhesive bond between thelens and the posterior mold section, starting around peripheral regionsof the lens and continuing towards the center of the lens, whereby theposterior mold section separates from the anterior mold section and thelens remains adhered to a concave surface of the anterior mold section.51. A method as claimed in claim 50, wherein applying the longitudinallydirected force to a central area of the concave surface of the posteriormold section includes pressing a free end of a pin against the centralarea.
 52. A method as claimed in claim 51, wherein the application ofthe force causes a rim of excess expelled cured lens material formedaround peripheral regions of the lens and adhered to surfaces of themold sections surrounding the lens to separate from the posterior moldsection and remain adhered to the anterior mold section.
 53. A method asclaimed in claim 52, wherein the step b) includes locating a secondflange projecting from a skirt portion of the anterior mold section in agap defined between a radially inwardly facing face of the first supportelement and a radially outwardly facing face of a second supportelement, the second support element being positioned between thelongitudinal axis and the first support element, whereby the anteriormold section is longitudinally spaced apart from the second supportelement.
 54. A method as claimed in claim 53, comprising, after step c):d) allowing the anterior mold section, upon separation therefrom of theposterior mold section, to drop onto a second face of the second supportelement whereby the second face comes into abutment with an outer convexsurface of the anterior mold section.
 55. A device for removing excessexpelled cured lens material adhered to a surface of a mold section, theexcess material being formed around peripheral regions of a cured lens,the lens being adhered to a concave molding surface of the mold section,the device comprising: a support element having a longitudinal axis anda face for supporting the mold section with the excess material; a firstmeans for supplying at least one jet of gas, the means being capable ofdirecting the gas at an interface between the excess lens material andthe surface of the mold section to which the excess material is adhered,the force of at least one jet of gas being sufficient to break theadhesive bond between the mold section and the excess lens material andto separate the excess lens material from the mold section.
 56. A deviceas claimed in claim 55, wherein the means for supplying at least one jetof gas comprises a first element positionable about the excess lensmaterial, the first element comprising a channel for supplying the gasand forming at least one jet.
 57. A device as claimed in claim 56,wherein the first element comprises a substantially tubular wall havingan inner surface, and the gas supply channel comprises an apertureformed in the inner surface of the tubular wall, the aperture beinglocated so that when the first element is brought into a pre-determinedposition about the excess material, the aperture is positionedsubstantially opposite the interface.
 58. A device as claimed in claim57, wherein the first element comprises a plurality of apertures spacedaround the perimeter of the inner surface of the tubular wall.
 59. Adevice as claimed in claim 58, wherein the inner surface is cylindricaland the first element comprises eight apertures spaced at 45° from eachother.
 60. A device as claimed in claim 59, wherein the device comprisesa vacuum means longitudinally spaced apart from the gas channel, thevacuum means being operable to draw the gas away from the mold section,thereby carrying therewith the separated excess material away from themold section.
 61. A device as claimed in claim 60, wherein the face forsupporting the mold is configured to abut an outer convex surface of themold section.
 62. A device as claimed in claim 61, wherein the face forsupporting the mold is in a form of an annular surface surrounding anaperture formed in the support element such that when the outer convexsurface of the mold section abuts the annular surface, a portion of theouter convex surface projects into the aperture, the aperture beingsized and shaped so that the outer convex surface remains spaced apartfrom surfaces defining the aperture.
 63. A device as claimed in claim62, wherein the second support element comprises of a pillar projectingfrom the post in the longitudinal direction.
 64. A device as claimed inclaim 63, wherein the second face comprises a chamfer formed between anend surface of the pillar and an inner surface defining the aperture.65. A device as claimed in claim 64, wherein the pillar comprises a pairof diametrically opposing flats on an outer surface of the pillar so asto provide a clearance for radial inward deformation of the skirt of theanterior mold section when the anterior mold section rests on the secondface.
 66. A device as claimed in claim 65, wherein the support elementis configured such that when the outer convex surface of the moldsection abuts the annular surface, the flange of the skirt portionremains free from contact with any of the surrounding surfaces.
 67. Adevice as claimed in claim 66, wherein the support element is configuredwith respect to the skirt portion of the mold section, so that when thesupport element is received within the skirt, sufficient spacing isprovided between inner surfaces of the skirt and outer surfaces of thesupport element to provide clearance for deformation of the skirt in theradial direction.
 68. A device as claimed in claim 67, comprising asecond means for applying a longitudinally directed force to a radiallyextending flange of a skirt of the mold section.
 69. A device as claimedin claim 68, wherein the second means comprises a pair of diametricallyspaced apart projections, each projection comprising an end face forabutting and pressing against the flange of the skirt of the moldsection.
 70. A device as claimed in claim 69, adapted to apply a forcesufficient to cause the surface of the mold section to which the excessmaterial is adhered to deflect in the direction of application of theforce thereby at least partially breaking the adhesive bond betweenperipheral regions of the excess lens material and the surface.
 71. Adevice as claimed in claim 69, adapted to apply a force sufficient tocause the molding surface of the mold section to deflect in thedirection of the application of the force thereby breaking the adhesivebond between the lens and the molding surface of the mold section atleast around peripheral regions of the lens, starting from an outer edgeof the lens and continuing in the direction of the center of the lens.72. A device as claimed in claim 71, wherein the first and second meansare connected to each other so that when the first means is positionedabout the excess material in order to apply at least one jet of gas, thesecond means applies the longitudinally directed force to the flange ofthe mold section.
 73. A method of removing excess cured lens materialadhered to a surface of a mold section, the excess material being formedaround peripheral regions of a cured lens adhered to a concave moldingsurface of the mold section, the method comprising the steps of: a)providing a support element having a longitudinal axis and a face forsupporting the mold section with the excess material; b) locating themold section on the support element; and c) directing at least one jetof gas at an interface between the excess lens material and the surfaceof the mold section to which the excess material is adhered, the forceof at least one jet being sufficient to break the adhesive bond betweenthe mold section and the excess lens material and separate the excesslens material from the mold section.
 74. A method as claimed in claim73, wherein step c) comprises positioning a first element about theexcess lens material, the first element comprising a channel forsupplying and forming at least one jet of gas, so that the channel ispositioned substantially opposite the interface.
 75. A method as claimedin claim 74, wherein step c) comprises directing a plurality of jets ofgas supplied from a plurality of channels spaced apart from each otheron the first element so as to encompass the excess material.
 76. Amethod as claimed in claim 75, wherein step c) comprises supplying thejets of gas from eight apertures spaced at 45° from each other along theperimeter of an inner surface of a tubular wall of the first element.77. A method as claimed in claim 76, the method further comprising: d)drawing the gas away from the mold section thereby carrying therewiththe separated excess material away from the mold section.
 78. A methodas claimed in claim 77, wherein the face of the support element is in aform of an annular surface surrounding an aperture formed in the secondsupport element, configured to abut an outer convex surface of the moldsection, such that when the outer convex surface abuts the annularsurface, a portion of the outer convex surface projects into theaperture while remaining spaced apart from surfaces defining theaperture, step b) of the method comprising locating the outer convexsurface of the mold section on the annular surface of the supportelement.
 79. A method as claimed in claim 78, comprising prior to orduring step c), applying a longitudinally directed force to a radiallyextending flange of a skirt of the mold section, the force beingsufficient to cause the surface of the mold section to which the excessmaterial is adhered to deflect in the direction of application of theforce thereby at least partially breaking the adhesive bond betweenperipheral regions of the excess lens material and the mold section andthereby assisting the gas jets in entering the interface.
 80. A methodas claimed in claim 79, comprising, upon separating the excess materialfrom the mold, continuing to apply a longitudinally directed force tothe radially extending flange, the force being sufficient to cause themolding surface of the mold to deflect in the direction of theapplication of the force thereby breaking the adhesive bond between thelens and the concave molding surface of the mold section at least aroundperipheral regions of the lens, starting from an outer edge of the lensand continuing in the direction of the center of the lens.
 81. A devicefor releasing peripheral regions of a cured lens adhered to a concavemold surface of a mold section, the device comprising: a support elementhaving a longitudinal axis and a face for supporting the mold section,the face being configured to abut an outer convex surface of the moldsection; the face for supporting the mold having the form of an annularsurface surrounding an aperture formed in the support element, such thatwhen the outer convex surface of the mold section abuts the annularsurface, a portion of the outer convex surface projects into theaperture, the aperture being sized and shaped so that the outer convexsurface remains spaced apart from surfaces defining the aperture; andmeans for applying a longitudinally directed force to a flangeprojecting from a skirt portion of the mold section, the force beingsufficient to cause the concave molding surface of the mold section todeflect in the direction of the application of the force therebybreaking the adhesive bond between the lens and the molding surface ofthe mold section at least around peripheral regions of the lens,starting from an outer edge of the lens and continuing in the directionof the center of the lens.
 82. A device as claimed in claim 81, whereinthe support element is configured such that when the outer convexsurface of the mold section abuts the annular surface, the flange of theskirt portion remains free from contact with any of the surroundingsurfaces.
 83. A device as claimed in claim 82, wherein the supportelement is configured with respect to the skirt portion of the moldsection, so that when the support element is received within the skirt,sufficient spacing is provided between inner surfaces of the skirt andouter surfaces of the support element to provide clearance fordeformation of the skirt in the radial direction.
 84. A device asclaimed in claim 83, wherein the means for applying a longitudinallydirected force comprises a pair of diametrically spaced apartprojections, each projection comprising an end face configured forabutting and pressing against the flange of the skirt portion.
 85. Adevice as claimed in claim 56, wherein the aperture of the supportelement is in a form of a bore.
 86. A device as claimed in claim 85,wherein the second support element is in the form of a pillar projectingfrom the post in the longitudinal direction.
 87. A device as claimed inclaim 86, wherein the annular surface comprises a chamfer formed betweenan end surface of the pillar and an inner surface defining the aperture.88. A device as claimed in claim 87, wherein the pillar comprises a pairof diametrically opposing flats on an outer surface of the pillar so asto provide a clearance for radial inward deformation of the skirt of themold section upon application of the longitudinally directed force. 89.A method of releasing peripheral regions of a cured lens adhered to aconcave molding surface of a mold section, the method comprising thesteps of: a) providing a support element having a longitudinal axis anda face for supporting the mold section, the face being configured toabut an outer convex surface of the mold section; the face forsupporting the mold being in a form of an annular surface surrounding anaperture formed in the support element, such that when the outer convexsurface of the mold section abuts the annular surface, a portion of theouter convex surface projects into the aperture, the aperture beingsized and shaped so that the outer concave surface remains spaced apartfrom surfaces defining the aperture; b) locating the outer convexsurface of the mold section on the support face; c) applying alongitudinally directed force to a flange projecting from a skirtportion of the mold section, the force being sufficient to cause theconcave molding surface of the mold section to deflect in the directionof the application of the force thereby breaking the adhesive bondbetween the lens and the molding surface of the mold section at leastaround peripheral regions of the lens, starting from thee center of thelens and continuing in the direction of the center of the lens.
 90. Amethod of claim 60 wherein step c) comprises pressing end faces of apair of diametrically opposed projections against the flange of theskirt portion and applying the longitudinally directed force to theflange with the projections.
 91. (canceled)
 92. (canceled) 93.(canceled)
 94. (canceled)
 95. (canceled)
 96. (canceled)
 97. (canceled)